Process for refining oleoresin



Patented Dec. 3, 1946 'raocsssroa' REFINING OLEORESI Ray V. Lawrence,Lake City, Fla assignor to Claude R. Wickard, as Secretary" ofAgriculture of the United Statesof America and to his successors inoffice No Drawing;

4 Claims.

amended Application September 23, 1941, Serial No. 412,004

(01. 260109) (Granted under the act of March 3, 1883, as

This application is made under the act of March 3, 1883, as amended bythe act of April 30, 1928, and the invention herein described andclaimed, if patented, may be manufactured and used by or for theGovernment of the United States of America tor governmental purposeswithout the payment to me of any royalty thereon. V

This invention relates to a process for the refining of crude pineoleoresin, commonly known as turpentine gum, from which an improvedgrade of rosin may be made.

Crude oleoresin is usually contaminated to some extent by dissolvediron. Upon the distillation of the oleoresin the iron remains in therosin. The presence of 0.1% iron will usually darken the rosin six ormore grades. Thisiron is not removed by any of the methods of refiningoleoresin 'now in use.

Crude oleoresin usually contains a considerable amount of chips, trashand other material insoluble in the oleoresin. I prefer to remove suchmaterial by filtration, or screening before removing dissolved iron.

My invention consists of a method of removing this iron, as well asother acid-soluble contaminating material from the oleoresin by washingthe oleoresin with an acid solution. The acid employed may be, forexample, hydrochloric, sulfuric, nitric, phosphoric, or acetic, or amixture of any of these acids. The oleoresin is separated from the acidwashing solution, washed with water and distilled in the usual manner.

One of'the methods used to improve the color of rosin contaminated withiron is to add oxalic acid crystals to the still during the process ofdistillation, or to the hot rosin after the turpentine has beendistilled. Such a process merely changes the color of theiron-contaminated rosin and does not remove the iron from the rosin.Thus, a rosin treated in this manner may have the color of WG and begraded as such, while it contains the impurities normally present in arosin of, grade H. The products made from such a resin will be such aswould be expected from grade H rosin; that is, the rosin producer hastemporarily disguised a low grade product, so that it will sell for ahigher price. 7

The density of crude oleoresin and water are so nearly the same that theseparation of the two is quite diificult. This separation may beaccomplished by decreasing thedensity of the oleoresin by diluting itwith a solvent whose density is less than that of water, or byincreasing the April 30, 1928; 370 O. G. 757) density of the acidsolution by dissolving in it some neutral or acid salt. I prefer theformer method of separation, and for a solvent I prefer to useturpentine, since such a method Will involve no problem in separatingthe solvent used from the turpentine originally present in theoleoresin. And, I prefer to add suflicient turpentine to the oleoresinso that the turpentine content is approximately to of the total productsobtained by distillation.

The filtered oleoresin containing the added turpentine may be allowed tosettle and. the water present in the original material may be drainedofi before washing the oleoresin with the acid solution to prevent thedilution of the acid solution by this water, or the oleoresin may bewashed with acid just as it comes from the filter.

Any strength acid solution that does not damage the oleoresin may beused. I prefer an aqueous solution Whose strength is between 1 normaland 2 normal. A small amount of solvent (such as alcohol or aceticacid), soluble in waterand oleoresin, may be added to the acid solutionto increase the efiiciency of the washing operation.

As an example of a method for carrying out the refining of oleoresin inaccordancewith my invention, a solution of oleoresin in turpentine,

which would yield 40% turpentine and rosin on distillation, is runthrough a jet, o some mixing device, into the bottom of a tank,partially filled with a 5% aqueous solution of sulfuric acid. Thetemperature of the oleoresin and acid solution is maintained atapproximately C. After being thoroughly mixed for two or three minutes,the oleoresin and the acid solution are allowed to separate by gravity,and the oleoresin is withdrawn from the acid tank. It is then washedwith water, either copiously or otherwise, to remove any entrained acid,and distilled in the usual manner.

- I do not limit myself to any particular apparatus, temperature,methods of mixing, dilutions of oleoresin, or concentrations of acid incarrying out my process, itbeing obvious that oleoresin varies inquality, composition and contaminating materials, which will necessitatevarious modifications in its treatment and handling.

Having thus described my invention, what I claim for Letters Patent is:V

1. The method of refining crude oleoresin containing iron compoundswhich comprises dissolving the oleoresin in turpentine, mixing theoleoresin solution with about a l to 2 normal aqueous solution ofsulfuric acid at a temperature of about 70 C. until the iron compoundsare dissolved out, separating and washing out the acid solution from theoleoresin solution and thereafter distilling off the turpentine.

2. The method of refining crude oleoresin con- 5 taining iron compoundswhich comprises dissolving the oleoresin in turpentine, mixing theoleoresin solution with about a 1 to 2 normal solu tion of a mineralacid at a temperature of about 70 until the iron compounds are dissolvedout,v

resin solution with about a 1 to 2 normal solution of hydrochloric acidat a temperature of about 70 C. until the iron compounds are dis solvedout, separating and washing out the acid solution from theoleoresinsolution and thereafter distilling off the turpentine.

4. The method of refining crude oleoresin containing iron compoundswhich comprises dissolving the oleoresin in turpentine, mixing theoleoresin solution with about a 1 to 2' normal solution of phosphoricacid at a temperature of about 70 C. until the iron compounds aredissolved out, separating and washing out the acid solution from theoleoresin solution and thereafte distilling l5 off the turpentine.

RAY V. LAWRENCE.

